1. Common instruments, equipment and application scope of organic chemistry experiments
The main metalware, electrical instruments and other equipment used in organic chemistry experiments are described below, and the small glass flasks are not introduced for the time being:
1. Metalware commonly used in organic experiments: iron frame, iron clip, iron ring, tripod, water bath, tweezers, scissors, triangular file, round file, plug press, puncher, steam generator, Gas lamps, stainless steel scrapers, lifting tables, etc.
2. Electrical instruments and small electromechanical equipment
(1) Electric heating sleeve It is a heater in which glass fiber is wrapped with electric heating wire and woven into a hat shape (see Fig. 2.3). When heating and distilling easily dyeable organic matter, since it is not an open flame, it has the advantage of not easily causing fire, and the thermal efficiency is also high. The heating temperature is controlled by a pressure regulating transformer, and the maximum temperature can reach about 400 °C, which is a simple and safe heating device in organic test. The volume of the electric heating sleeve is generally matched with the volume of the flask, and is available in various specifications from 50 mL. The electric heating sleeve is mainly used as a heat source for reflow heating. When it is used for distillation or vacuum distillation, as the distillation progresses, the contents of the bottle are gradually reduced. At this time, heating with the electric heating sleeve causes the bottle wall to overheat and causes the distillate to be scorched. If the electric heating jacket of the larger one is used, the height of the lifting platform of the electric heating sleeve is continuously reduced during the distillation process, and the scorching phenomenon is reduced.
(2) Rotary evaporator The rotary evaporator is composed of a condenser and a receiver that is driven by a motor to rotate the evaporator (round bottom flask) (see Figure 2.4). It can be operated under normal pressure or reduced pressure, and can be fed at one time. It is also possible to inhale the evaporation liquid in batches. Due to the constant rotation of the evaporator, zeolite can be avoided without bumping. When the evaporator rotates, the evaporation surface of the liquid is greatly increased, and the evaporation speed is accelerated. Therefore, it is an ideal device for concentrating solutions and recovering solvents.
(3) Electric agitator Electric agitator (or small motor with pressure regulating transformer) is used for stirring in organic experiments. Generally applicable to solutions such as oil and water or solid-liquid reactions. Not suitable for overly viscous gelatinous solutions. If it is overloaded, it is very hot and burns. It must be connected to the ground wire during use. It should be kept clean and dry, moisture-proof and corrosion-proof. Bearings should always be refueled to maintain lubrication.
(4) The magnetic stirrer consists of a soft iron (called a magnetic bar) sealed with glass or plastic and a rotatable magnet. Put the magnetic rod into the reagent container for stirring, place the container on the agitator tray with the rotating magnetic field, turn on the power, change the magnetic field due to the rotation of the internal magnet, and rotate the magnetic rod inside the container. , to achieve the purpose of mixing. A general magnetic stirrer (such as a Type 79-1 magnetic stirrer) has a knob that controls the speed of the magnet and a temperature-controlled heating device.
(5) The oven oven is used to dry glass instruments or to dry articles that are non-corrosive and do not decompose when heated. Volatile flammable materials or glass instruments that have just been rinsed with alcohol or acetone should not be placed in an oven to avoid an explosion.
Oven use instructions: After the power is connected, the heating switch can be turned on, and then the temperature control knob is rotated clockwise from the “0†position to a certain extent (depending on the oven model). At this time, the oven starts to heat up, and the red indicator light Shine. If there is a blower, turn on the blower switch to make the blower work. When the thermometer rises to the working temperature (observed from the thermometer reading on the top of the oven), the thermostat knob is slowly rotated counterclockwise, and the indicator light just turns off. At the alternate point where the indicator light is extinguished, it is the constant temperature fixed point. Generally, when drying the glass instrument, it should be drained first. When there is no water drop, it should be placed in the oven. The temperature is raised and the temperature is controlled at about 100-120 °C. The ovens in the laboratory are common instruments. When placing the glass instruments in the oven, they should be placed from top to bottom in order to prevent the residual water droplets from flowing down to cause the underlying glassware to burst. When removing the dried instrument, apply a dry cloth to prevent burns. Do not touch the water after removal to prevent it from bursting. After taking out the hot glassware, if it is allowed to cool itself, the wall will often be condensed. The air blower can be blown into the cold air to help it cool down, so as to reduce the condensation of water on the wall.
(6) The hair dryer used in the hair dryer laboratory should be able to blow cold air and hot air for drying glass equipment. It should be placed in a dry place to prevent moisture and corrosion. Regular lubrication
(7) Voltage regulating transformer The voltage regulating transformer is a device for adjusting the power supply voltage. It is commonly used to adjust the temperature of the heating electric furnace and adjust the rotating speed of the electric agitator. Please pay attention when using:
1 The power supply should be connected to the terminal marked as the input terminal, and the terminal of the output terminal should be connected with the wire of the agitator or electric furnace. Do not connect the wrong one. At the same time, the transformer should have good grounding.
2 Adjust the knob should be even and slow to prevent sparks and carbon brush contact points from being damaged due to severe friction. If the carbon brush is worn out, it should be replaced.
3 Long-term overload is not allowed to prevent burning or shorten the service life.
4 The contact surface of the carbon brush and the winding group should be kept clean, and the dust is often wiped off with a soft cloth.
5 After use, turn the knob back to zero position, cut off the power supply, and put it in a dry and ventilated place, not near corrosive objects.
3, other equipment
(1) Platform scale In the organic synthesis laboratory, the instrument commonly used to weigh the mass of an object is a scale. The maximum weighing of the scale is 1000g, or 500g, which can be weighed to 1g. If using a pharmaceutical platform scale (also known as a small scale), the maximum weighing is l00g, which can be weighed to 0.1g. Although the maximum weighing of these scales is different, the principle is the same. They all have a lever with a fulcrum in the middle, and each side of the lever is equipped with a weighing pan (see Figure 2.5). The weighing pan on the left side is placed on the weighing object, the weight on the right weighing pan is placed, and the pointer is connected to the lever fulcrum. The tilt of the pointer indicates that the quality of the two discs is not equal. There is a swimming ruler parallel to the lever and an active travel code on the ruler. Before weighing, first observe whether the two arms are balanced and whether the pointer is in the center of the scale. If it is not in the center, you can adjust the balance screws at both ends so that the pointer points to the center of the scale and the arms are balanced.
When weighing, place the object on the left plate, add the weight on the right plate, use the tweezers (do not directly use the hand) to increase the weight first, then add the smaller one, add or subtract to 10g (the small scale is 5g) For the following quality, you can move the game code until the pointer is in the center of the ruler, indicating that the two sides are of equal quality. The number of grams of the weight on the right plate plus the upstream code on the tour code is the mass of the object. After the scale is used up, put the weight back into the box and restore the cursor to scale 0. The scale should be kept clean and the object should not be placed directly on the tray. Instead, it should be weighed in a clean, dry watch glass, sulfuric acid paper or beaker.
(2) When the torque balance is used for semi-micro preparation, the torque balance can be used because the sensitivity of the ordinary scale is not enough. The torque balance can be accurate to 0.01g. Adjust the foot screws to balance the left and right before use. When weighing lg or less, it can be adjusted by rotating the mass knob.
(3) cylinder
Also known as a high pressure gas cylinder, it is a container for storing or transporting gas under pressure, usually cast steel, low alloy steel, and the like. Hydrogen, oxygen, nitrogen, air, etc. are in a compressed gas state in the cylinder, and carbon dioxide, ammonia, chlorine, petroleum gas and the like are liquefied in the cylinder. The acetylene cylinder is filled with a porous substance (such as wood chips, activated carbon, etc.) and acetone, and the acetylene gas is dissolved therein under pressure. In order to prevent the mixing of various cylinders, the color of the bottle body, the horizontal bar and the standard word are uniformly defined in the country. The color standards of several commonly used cylinders are now summarized in Table 1.1.
Note when using cylinders:
1 The cylinder should be placed in a cool, dry place away from heat sources to avoid direct sunlight. Hydrogen cylinders should be placed in a gas cylinder room separate from the laboratory. Steel cylinders should be placed as little as possible in the laboratory.
2 When carrying the cylinder, screw the cap, put on the rubber band, and gently handle it to prevent it from falling or vibrating.
3 When using the cylinder, if it is placed upright, it should be bracketed or tied with wire to avoid falling; if it is placed horizontally, it should be stabilized to prevent rolling, and oil and other organic substances should be prevented from smudging the cylinder.
4 cylinders should be used with decompression tables. Generally, the flammable gas (hydrogen, acetylene, etc.) cylinder valve threads are reversed, and the non-combustible or combustion-supporting gas (nitrogen, oxygen, etc.) cylinder valve threads are positive. Various decompression tables must not be mixed. When opening the valve, stand on the other side of the decompression table to prevent the decompression table from coming out and being injured.
5 The gas in the cylinder is not available, and should be kept above 0.5% gauge pressure to prevent danger when refilling.
6 When using flammable gas, there must be a device to prevent tempering (some decompression tables have such a device). A fine copper wire mesh is placed in the conduit, and a liquid seal is added to the pipeline to protect it.
7 cylinders should be pressure tested regularly (the general cylinders are inspected once every three years). If it is not tested or the corrosion is serious, it shall not be used, and the leaking cylinder shall not be used.
(4) Decompression gauge The decompression gauge consists of a total pressure gauge indicating the cylinder pressure, a pressure reducing valve for controlling the pressure, and a partial pressure gauge after the pressure reduction. When using it, be careful to connect the decompression meter to the cylinder (do not screw it!), then turn the pressure regulating valve of the decompression table to the loosest position (ie, closed). Then open the cylinder total gas valve, the total pressure gauge shows the total gas pressure inside the bottle. After checking the joints (with soapy water) without leaking, slowly tighten the pressure regulating valve to make the gas slowly pass to the system. When using, first close the cylinder total valve, empty the system gas, wait until the total pressure gauge and the sub-pressure gauge point to 0, then loosen the pressure regulating valve. If the connection between the cylinder and the decompression table is leaking, a gasket should be added to seal it. It must not be plugged with hemp or the like. In particular, the oxygen cylinder and the decompression table must not be oiled. This should be especially noted.
Second, the common equipment for organic experiments
In order to facilitate the review and comparison of the basic operations common in organic chemistry experiments, the instrumentation of reflux, distillation, gas absorption and agitation is discussed here.
1. Reflow Device Many organic chemical reactions need to be carried out near the boiling point of the solvent or liquid reactant of the reaction system. In this case, a reflux device is used (see Figure 2.6). Figure 2.6(1) is a general heating reflow device; Figure 2.6(2) is a moisture-proof heating reflow device; Figure 2.6(3) is a reflow device with a gas generated in the absorption reaction, suitable for water-soluble gas during reflow (eg: Experiments produced by HCl, HBr, SO2, etc.; Figure 2.6(4) is a device capable of simultaneously dropping liquid at the time of reflux. Before reflux heating, the zeolite should be placed first. According to the boiling temperature of the liquid in the bottle, it can be directly heated by water bath, oil bath or asbestos net. Under the conditions, the asbestos net is generally not used to directly heat with open flame. The rate of reflux should be controlled so that liquid vapor infiltration does not exceed two spheres.
2. Distillation unit distillation is a common method for separating two or more liquids having a large difference in boiling point and removing an organic solvent. Several common distillation units (see Figure 2.7) can be used for different requirements. Figure 2.7(1) is the most commonly used distillation unit. Since the outlet of this unit is open to the atmosphere, it may escape the vapor of the distillate. If the low-boiling liquid which is volatile is distilled, the branch of the liquid-pipe should be connected to the rubber tube. , to the sink or outside. The branch pipe is connected to a drying pipe and can be used as a moisture-proof distillation.
Figure 2.7 (2) is a distillation apparatus using an air condensing tube, which is commonly used to distill liquids having a boiling point above 140 °C. If a straight water condensing tube is used, the condensing tube will burst due to the high temperature of the liquid vapor. Figure 2.7 (3) is a device for evaporating a larger amount of solvent. Since the liquid can be continuously added from the dropping funnel, the speed of dropping and steaming can be adjusted, and a larger distillation bottle can be avoided.
3. Gas absorption device The gas absorption device (see Figure 2.8) is used to absorb irritating and water-soluble gases such as HCl, SO2, etc. generated during the reaction. Among them, Figures 1.8(1) and 18.(2) can be used as absorption devices for small amounts of gas. The glass funnel in 2.8(1) should be slightly inclined so that the funnel is half in the water and half on the water. In this way, it is possible to prevent the gas from escaping and prevent the water from being sucked back into the reaction bottle. If a large amount of gas is generated during the reaction or the gas escapes quickly, the device of Figure 2.8(3) can be used. Water flows from the upper end (water that can be discharged from the condenser) into the filter bottle and overflows on a constant plane. . The thick glass tube just protrudes into the water and is sealed by water to prevent gas from escaping into the atmosphere. The thick glass tube in the figure can also be replaced by a Y-shaped tube.
4. Stirring device When the reaction is carried out in a homogeneous solution, it is generally possible not to stir because the solution has a certain degree of convection during heating, thereby keeping the liquid portions uniformly heated. If it is a heterogeneous reaction, or one of the reactants is gradually added dropwise, in order to mix it as quickly and uniformly as possible, to avoid the occurrence of other side reactions or decomposition of organic matter due to local overheating; sometimes the reaction product is solid. If it is not stirred, it will affect the smooth progress of the reaction; in these cases, stirring is required. The use of a stirring device in many synthetic experiments not only allows better control of the reaction temperature, but also shortens the reaction time and increases the yield. The commonly used mixing device is shown in Figure 2.9. Figure 2.9(1) is an experimental device capable of simultaneously stirring, refluxing and adding liquid from a dropping funnel; the device of Figure 2.9(2) can simultaneously measure the temperature of the reaction; Figure 2.9(3) is a stirring device with a drying tube Figure 2.9(4) is magnetic stirring. Â
5, instrument device method Organic chemistry experiment commonly used glass instrument device, generally with iron clips to the instrument in turn fixed on the iron frame. The double clamp of the iron clip should be attached with soft materials such as rubber and flannel, or wrapped with asbestos rope and cloth strip. If the iron clamp directly clamps the glass instrument, it is easy to pinch the instrument. When clamping the glassware with the iron clip, first clamp the double clamp with the left hand finger, and then tighten the iron clamp screw. When the clamp finger feels the screw touches the double clamp, it can stop the rotation, so that the object is not loose. . Taking the reflow device [Fig. 1.6(2)] as an example, the device is first clamped to the bottle neck of the round bottom flask with iron clamp according to the heat source level (generally based on the height of the tripod), and is vertically fixed on the iron frame. The iron frame should be facing the outside of the test bench, not to be skewed. If the iron frame is skewed, the center of gravity is inconsistent and the device is unstable. Then, the lower end of the spherical condensation tube is fixed to the top of the flask with the iron clip vertically, and then the iron clip is loosened, the condensation tube is put down, the grinding port is tightened, and then the iron clip is slightly tightened to fix the condensation tube. So that the iron clip is located somewhere in the middle of the condenser tube. Connect the condensate with a suitable rubber hose with the inlet below and the outlet above. Finally, press 1.6(2) to dry the tube at the top of the condenser.
General rules for installing instruments:
(1) first down and then up, from left to right;
(2) Correct, tidy, stable, and correct; its axis should be parallel to the edge of the test bench.
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